JP2003121107A - Rotary position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize and simplify a rotary position detector. SOLUTION: The rotary position detector has a sensor head (SH) which is constituted by arranging at least a pair of coils excited by an AC signal over a part of a predetermined angle-of-rotation range, and a magnetic response member (RP) arranged so as to be rotationally displaced relatively with respect to the sensor head (SH). The magnetic response member (RP) has a shape generating not only output showing differential characteristics in the respective coils corresponding to a relative rotary position, but also output corresponding to a plurality of cycles during one rotation. By this constitution, the sensor head (SH) is arranged so as to be biased to a place of an angle range where no obstacle is present to make it possible to detect rotation with high accuracy. Therefore, an effective result is obtained in such a case that the position detector is arranged within an existing machine of a narrow range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary type position detecting device including a coil excited by an alternating current and a magnetic body or a conductive body which is relatively displaced with respect to the coil. It is suitable for detecting the rotational position over an angular range, and in particular, it uses only a primary coil excited by a one-phase alternating current to output an output AC signal showing the amplitude function characteristics of a plurality of phases depending on the rotational position to be detected. About what to generate.

[0002]

2. Description of the Related Art An induction type rotational position detecting device which produces a two-phase output (output of sine phase and cosine phase) with one-phase excitation input is known as a "resolver", and one with three-phase excitation input. What produces a phase output (three phases shifted by 120 degrees) is known as "synchronization". The oldest conventional resolver has two poles (sine pole and cosine pole) that are orthogonal to each other at a mechanical angle of 90 degrees on the stator side and a primary winding on the rotor side. It is a thing. This is a drawback because these types of resolvers require a brush to make electrical contact with the primary winding of the rotor. On the other hand, the existence of a brushless resolver that does not require a brush is also known. The brushless resolver is provided with a rotary transformer that replaces the brush on the rotor side. However, since such a brushless resolver has a structure in which a rotary transformer is provided on the rotor side, it is difficult to downsize the device, and there is a limit to downsizing, and the device configuration is reduced by the amount of the rotary transformer. Since the number of parts increases, it also leads to an increase in manufacturing cost.

On the other hand, the primary winding and the secondary winding are arranged on a plurality of salient poles on the stator side, and the rotor is made of a magnetic material of a predetermined shape (eccentric circle shape, elliptical shape, or shape having protrusions). Then, based on that the gap between the stator salient pole and the rotor magnetic body changes according to the rotational position, a magnetic resistance change corresponding to the rotational position is generated, and an output signal corresponding to this is obtained. A contactless variable magnetic resistance type rotational position detecting device has been known as a product name "Micro Thin" for a long time. Further, a rotary position detecting device based on the same variable reluctance principle is disclosed in, for example, Japanese Patent Laid-Open No. 55-46862.
It is shown in JP-A-55-70406 and JP-A-59-28603. In this case, the position detection method based on the output signal includes the phase method (the detected position data corresponds to the electrical phase angle of the output signal) and the voltage method (the detected position data is the voltage level of the output signal). Both of which are compatible with) are known. For example, when the phase method is adopted, each primary winding arranged at a different mechanical angle, such as a two-phase excitation input or a three-phase excitation input, is excited by a plurality of phases out of phase and the electric A one-phase output signal whose phase angle is shifted is generated. Further, when the voltage method is adopted, the relationship between the primary winding and the secondary winding is opposite to that of the phase method described above, and a plurality of phase outputs are generated by the one-phase excitation input as in the above “resolver”.

A rotary position detecting device such as a "resolver" which produces a plurality of phase outputs with a one-phase excitation input is typically configured to produce a two-phase output of a sine phase output and a cosine phase output. . Therefore, the conventional non-contact type
In the variable magnetic resistance type resolver type rotational position detecting device, at least the stator has a four-pole configuration, and each pole is arranged at an interval of 90 degrees in mechanical angle. The second pole spaced apart is in the cosine phase, the third pole further spaced 90 degrees is in the negative sine phase, and the fourth pole further spaced 90 degrees is in the negative cosine phase. In that case, the rotor is made of a magnetic material or a conductive material in order to cause a change in magnetic resistance according to rotation for each stator pole, and its shape is a periodic shape such as an eccentric shape, an elliptical shape, or a gear shape. Is formed. And
Each stator pole is provided with a primary coil and a secondary coil,
The magnetic resistance of the magnetic circuit passing through the stator poles changes as the gap between each stator pole and the rotor changes corresponding to the rotational position of the rotor, and based on this, the primary coil and the secondary coil in the stator poles are changed. The degree of magnetic coupling between the two changes according to the rotational position, and thus the output signal corresponding to the rotational position is induced in the secondary coil, and the peak amplitude characteristic of the output signal of each stator pole is periodic. The function characteristics are shown.

[0005]

The conventional contactless variable magnetic reluctance type resolver type rotary position detecting device as described above is a primary-secondary induction type in which a primary coil and a secondary coil are provided. Therefore, the number of coils increases, and therefore,
There is a limit to downsizing the structure, and also a limit to reducing the cost. Further, since the conventional rotational position detection device has a configuration in which a plurality of stator poles are arranged at equal intervals over the entire rotation, there is a limit to the applicable place and space due to the structural limitation. Further, in the conventional rotational position detecting device, even when the two-phase output of sine and cosine is obtained, the stator cannot have a simple two-pole structure, and the four-pole structure has to be used. There was a limit to downsizing the structure.

The present invention has been made in view of the above points, and an object thereof is to provide a rotary type position detecting device having a small size and a simple structure. Further, it is an object of the present invention to provide a rotary type position detection device which can take a wide range of usable phase angles and can detect with high resolution even when the displacement of the detection target is minute.

[0007]

A rotary type position detecting device according to the present invention is a coil portion in which at least one pair of coils excited by an AC signal are arranged over a predetermined partial rotation angle range. The coils of the pair of coils are arranged at intervals corresponding to a predetermined rotation angle, and are magnetically responsive members arranged so as to be rotationally displaced relative to the coil portion. The relative rotational position of the member and the coil portion changes according to the rotation of the object,
The impedance of the coil is changed according to the relative rotational position, and the voltage generated in the coil is increased or decreased while the relative rotational position changes over a predetermined rotation angle range based on the impedance change.
The pair of coils is configured so that an increase / decrease in voltage of each coil shows a differential characteristic, and has a shape that causes the impedance change for a plurality of cycles in one rotation. A circuit for extracting the difference between the voltages generated in the coils of the respective coils and generating an AC output signal having a predetermined cyclic amplitude function as an amplitude coefficient for each coil, wherein the cyclic amplitude of each AC output signal is The function has a difference in its periodic characteristic by a predetermined phase.

Further, as a preferred embodiment of the present invention, two pairs of the coils are provided, and the circuit has an AC output signal having a sine function as an amplitude coefficient and a cosine function as an amplitude coefficient from each coil pair. And an alternating current output signal that it has.

The magnetically responsive member typically comprises at least one of a magnetic material and a conductor. When the magnetically responsive member is made of a magnetic material, the inductance of the coil increases as the area of the member facing the coil increases, and the electrical impedance of the coil increases. Voltage) increases. Conversely, as the area of the magnetically responsive member facing the coil becomes narrower, the inductance of the coil decreases, the electrical impedance of the coil decreases, and the voltage across the terminals of the coil decreases. In this way, as the relative rotation position of the magnetically responsive member with respect to the coil changes over a predetermined rotation angle range, the terminal voltage of the coil increases or decreases as the detection target rotates.

Here, the AC signal flowing through the coil is converted to sin.
If the amplitude coefficient component generated by this increase / decrease change is represented by a function A (θ) with the rotation angle θ as a variable, the terminal voltage of the coil can be represented by A (θ) sinωt. In this case, the amplitude coefficient component A (θ) increases / decreases with rotation, but its value is only a positive value. For example, if the curve of the increase / decrease change of the amplitude coefficient component A (θ) exhibits a characteristic that approximates to a sine curve, and its peak value is P, it is typically shown by an equation such as A (θ) = P0 + Psinθ. It is what is done. Where P
0 ≧ P. That is, it is a characteristic that the value of Psinθ is offset in the plus direction by a certain offset value P0.

According to the present invention, as described above, for example,
When one coil pair has a sine phase, the increase / decrease in the terminal voltage of each coil in the one coil pair exhibits a differential characteristic. Therefore, if one is (P0 + Psinθ) sinωt, the other is (P0−Psinθ). sin ωt. Taking out the difference between them, (P0 + Psinθ) sinωt-{(P0-Psin
θ) sinωt} = 2Psinθsinωt. When the other coil pair is the cosine phase, the increase and decrease in the voltage across the terminals of each coil in the coil pair show a differential characteristic. Therefore, when the difference between the two is taken out, (P0 + Pcosθ) sinωt-{( P0-Pcos
θ) sinωt} = 2Pcos θsinωt. Although such a differential combining principle is common to the conventionally known resolvers, the conventional resolver has a primary and secondary resolver.
Although the secondary coil is required, according to the present invention, since only the primary coil needs to be provided and the secondary coil is not necessary, a rotary type position detecting device having a simple coil structure and a simple structure is provided. It will be possible to provide.

According to the present invention, the coil portion is provided within a limited predetermined angle range within one rotation, and is adapted to detect a rotational position within the limited predetermined angle range. There is. In this case, as will be described later in detail, with respect to the rotational displacement in the predetermined limited mechanical rotation angle range, the phase detection scale within the predetermined limited range (for example, Position detection data can be obtained within a range of 60 degrees. That is, although it is a detection scale within a predetermined limited range,
It is possible to obtain two AC output signals similar to those of the resolver, that is, a sine phase output signal (sin θsin ωt) and a cosine phase output signal (cos θ sin ωt). Such a biased arrangement of coil portions is effective when the rotary position detecting device according to the present invention is installed later in an existing machine. For example, when an obstacle already exists in a predetermined angle range on the rotation axis to be detected and it is impossible to install the stator coil for one full rotation, the position is set in the angle range where the obstacle does not exist. This is advantageous because it is possible to install the coil portions having a biased arrangement.

When a non-magnetic good conductor such as copper, that is, a diamagnetic material is used as the magnetic responsive member, the inductance of the coil decreases due to eddy current loss, and the coil responsive to the proximity of the magnetic responsive member. The voltage between terminals will decrease. Also in this case, it is possible to detect in the same manner as above. As the magnetic response member, a hybrid type member in which a magnetic body and a non-magnetic good conductor (diamagnetic body) are combined may be used.

As an example, around the coil portion,
It is advisable to provide a magnetic shield member for blocking the external magnetism to the coil portion. The magnetic shield member may be made of a magnetic substance and / or a conductor. When the magnetic shield member made of a magnetic material is used, a magnetic circuit for magnetism from the outside is formed through the magnetic material, and it is possible to shield the internal coil portion from the outside magnetism. When a magnetic shield member made of a conductor is used, the magnetism from the outside is attenuated by the eddy current loss at the location of the conductor, so that the external magnetism with respect to the internal coil portion is shielded. A combination of a magnetic body and a conductor may be used as the magnetic shield member.

According to another aspect, the present invention comprises a rotor portion having a predetermined shape and formed of a magnetically responsive member attached to a rotary shaft to be detected made of a magnetic material, and a stator having a coil portion excited by an AC signal. However, the relative rotational position of the magnetically responsive member and the coil portion changes according to the rotation of the rotating shaft, and the impedance of the coil portion changes according to the change of the relative rotational position. In the rotational position detecting device adapted to generate an output signal according to the above, a magnetic shield member is provided at a joint portion for fixing the rotor portion to the rotation shaft, and the magnetic shield member leaks to the rotor portion through the rotation shaft from the outside. The magnetic field is shielded by the magnetic shield member.

[0016] According to another aspect, a rotor part having a predetermined shape, which is a magnetically responsive member, is attached to the rotary shaft to be detected, and a stator having a coil part excited by an AC signal. The relative rotational position of the magnetically responsive member and the coil portion changes according to the rotation,
In a rotational position detecting device configured to change the impedance of the coil portion according to the change in the relative rotational position and generate an output signal according to the change in the impedance, a coil position is provided around the coil portion with respect to the coil portion. It is characterized in that a magnetic shield member for shielding the magnetism from the outside is provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 (A) is a schematic front view showing the structure of a rotary type position detecting device according to an embodiment of the present invention, FIG. 1 (B) is a schematic side sectional view thereof, and FIG. 1 (C) is the rotary type position detecting device. 3 is an enlarged perspective view of a detection unit in FIG. FIG. 2 is an electric circuit diagram related to the sensor coil in the same device. The rotary type position detecting device shown in this embodiment includes a separate type sensor head which can be arranged at an appropriate position of a rotating body (for example, a rotor) to be detected in order to detect a rotation angle of a motor. It is a rotary position detection device. The rotary type position detecting device detects a rotation angle of a body plate P, which is a rotating body and is attached to a rotating shaft MJ so as to rotate with the driving of a motor M or the like, and uses the sensor coils L1 to L4. A separate type sensor head SH, which is a coil section including a plurality of detecting sections S1 to S4, respectively, and a magnetic response member of a predetermined shape which is integrally attached to the main body plate P together with a mounting screw T together with a shield ring SR ( For example, the sensor rotor plate RP is composed of a magnetically responsive member made of a magnetic material such as iron). That is, in this rotary type position detection device, the sensor rotor plate R that rotates together with the body plate P about the rotation axis MJ is used.
The rotation of P is detected by a plurality of detection units S1 to S of the sensor head SH.
4 simultaneously detects the rotation axis M of the motor M.
The rotation angle of J can be detected.

The sensor head SH includes a plurality of (four in this embodiment) detectors S1 to S4 as detecting coils for detecting the rotation of the sensor rotor plate RP. Each of the detection units S1 to S4 is directed to the rotation center position of the rotation axis MJ according to the curvature of the main body plate P, and the detection units S1 to S4 are spaced apart from each other on the sensor head SH at predetermined intervals in the circumferential direction. Are arranged to
The intervals are, for example, intervals of 15 degrees with respect to the rotation center position of the rotation axis MJ. Each detector S1 (S2
To S4) are different magnetic cores C1 (C2 to C4).
4) includes two sensor coils L1 (L1 to L4) wound in opposite directions, and the magnetic flux Φ passing through the two sensor coils L1 (L2 to L4) is the rotation axis. It is oriented in the axial direction of the MJ. The magnetic core C1 (C2-C2) in which the sensor coil L1 (L2-L4) is arranged
C4) is, for example, a laminated silicon steel plate having a shape in which a plurality of silicon steel plates formed in a letter “C” as shown in FIG. 1C are stacked. When the magnetic core C1 (C2 to C4) is made of a laminated silicon steel plate, the sensor coil L1 (L2
.About.L4), the eddy current generated when the magnetic fluxes respectively generated are changed can be made as small as possible, which can reduce the eddy current loss, which is very preferable. Further, by winding the sensor coils L1 to L4 around the magnetic cores C1 to C4 formed in the shape of “C”, a magnetic path (that is, a magnetic flux circuit) for passing magnetic flux generated in the sensor coils L1 to L4 is formed. Since the magnetic field is positively generated, the influence of other magnetic flux generated externally can be reduced, which is preferable.

By arranging and arranging each of the sensor coils L1 to L4 and the surface of the sensor rotor plate RP so that a space is formed between them, the sensor rotor plate RP can detect the sensor portion S1 of the sensor head SH. ~ S4
Rotates in a non-contact state with respect to. The distance of this void is
The relative arrangement of the sensor rotor plate RP and the sensor head SH is determined via a mechanism (not shown) so as to be kept constant. When the sensor rotor plate RP is made of a magnetic material, the sensor rotor plate RP formed in a predetermined shape, for example, a petal shape, rotates according to the rotational position of the main body plate P, so that the sensor coils L1 to L4 are magnetized. The degree of binding changes. That is, the facing void area between the sensor coils L1 to L4 and the surface of the sensor rotor plate RP changes, so that the sensor coils L1 to L4 pass through the magnetic cores C1 to C4.
The amount of magnetic flux penetrating through the sensor changes, and thus the degree of magnetic coupling of each of the sensor coils L1 to L4 changes. As the degree of magnetic coupling to the sensor coils L1 to L4 increases, the inductance of the sensor coils L1 to L4 increases, and thus the sensor coils L1 to L4.
4 increases, and the voltage generated in the sensor coils L1 to L4, that is, the voltage between terminals increases. On the contrary, as the degree of magnetic coupling to the sensor coils L1 to L4 decreases, the inductance of the sensor coils L1 to L4 decreases, so that the electrical impedance of the sensor coils L1 to L4 decreases. And the voltage generated in the sensor coils L1 to L4, that is, the voltage between terminals decreases. In this way, the voltage across the terminals of the sensor coils L1 to L4 gradually increases while the relative rotational position of the sensor rotor plate RP with respect to the detection units S1 to S4 changes over a predetermined rotation angle range as the detection target rotates. Or gradually decrease).

The sensor rotor plate RP is a magnetically responsive member, and its shape is designed to be an appropriate shape so as to obtain an ideal sine function curve. According to the design / arrangement conditions of the sensor coils L1 to L4, for example, the shape of the sensor rotor plate RP is 6 in order to obtain a curve of a sine function of 1 cycle per 1/6 rotation of the rotation axis MJ. Shape of teeth or 6 petals, 1/4 of axis of rotation MJ
In order to obtain a curve of a sine function of one cycle per rotation, the shape of the sensor rotor plate RP can be the shape of four teeth or four petals. How to design the shape of the sensor rotor plate RP is not the object of the present invention, and the shape of the rotor used in the known / unknown variable reluctance type rotation detector is the sensor rotor plate RP. Since it may be adopted as the shape of the RP, here, the shape shown in FIG.
The petal-shaped sensor rotor plate RP will be briefly described.

The sensor rotor plate RP shown in the embodiment of FIG. 1 (A) has a plurality (per tooth or six petals in this embodiment) per revolution, such as a multi-tooth or multi-petal that rotates together with the rotation axis MJ. N) The detectors S1 to S4 are shaped so as to cause a change in the magnetic resistance in a cycle, and each of the detection units S1 to S4 rotates 1 / N of the sensor rotor plate RP (that is, 360 degrees /
The structure is arranged within a narrow range of N).
In the embodiment of FIG. 1A, 360 degrees / N = 360/6 =
Within the mechanical angle range of 60 degrees, the four detectors S1 to S4 are "6".
The sensor heads SH are arranged at intervals of 0 degree / 4 = 15 degrees. Each detection unit S1 arranged on the sensor head SH
The sensor coils L1 to L4 of S4 to S4 face each other in the axial direction of the rotation axis MJ, and the sensor coils L1 to L4 have the surface of the sensor rotor plate RP having 6 cycles of unevenness per rotation. To face. The sine function sin θ and the cosine function cos θ obtained by this are
The accuracy is N = 6 times the actual mechanical angle of the rotation axis MJ. For example, if the actual mechanical angle of the rotation axis MJ is ψ, then sin θ = sin N ψ and cos θ = cos N ψ. In the present embodiment, since each of the detection units S1 to S4 of the sensor head SH is arranged within a narrow range of 1 / N rotation (that is, 360 degrees / N), the mounting space of the sensor head SH is large. Very suitable for applications where is limited to a narrow range. From the above,
What is important about the shape of the sensor rotor plate RP is not what kind of shape the sensor rotor plate RP, that is, the predetermined shape of the magnetically responsive member, is, in short, according to the change in the rotational position of the sensor rotor plate RP. It is sufficient that the inductance change, that is, the impedance change, of each of the sensor coils L1 to L4 is designed to have an appropriate shape as much as possible so as to be similar to an ideal sine function curve.

In the above-described embodiment, the sensor head SH has four poles in which four detectors S1 to S4 are arranged. However, the present invention is not limited to this, and a plurality of detectors S1 to S4 are formed. Anything will do. That is, any configuration may be used as long as an ideal sine function and cosine function can be obtained with the rotation of the sensor rotor plate RP. Also, an example has been shown in which two sensor coils L1 to L4 are arranged so as to face each other such that the sensor rotor plate RP is sandwiched between the respective poles of the sensor head SH.
The sensor coils L1 to L4 may be arranged on the same side surface of the sensor head SH, one for each pole. However, when two sensor coils L1 to L4 are arranged facing each other for each pole of the sensor head SH so as to sandwich the sensor rotor plate RP as described above, the deviation of the sensor rotor plate P due to the occurrence of calibration occurs. It is preferable because the fluctuation of the magnetic flux due to the influence of can be offset. The body plate P may be made of a magnetic material such as iron. In this case, the body plate P shields the magnetic flux generated on the motor M side, and the magnetic flux generated on the motor M side does not leak to the sensor head SH side. That is, the sensor coil L1 of the sensor head SH
Since ~ L4 is not affected by the magnetic flux generated on the motor M side, the rotational position can be accurately detected, which is preferable. Further, the shield ring SR is preferably composed of a diamagnetic material having a diamagnetic property such as gold, copper or silver. In this case, the magnetic flux generated from each of the sensor coils L1 to L4 does not leak to the motor side M, so that the rotation angle can be accurately detected.

FIG. 3A shows a curve of an ideal sine function of the impedance change of one sensor coil L1 with respect to the change of the rotation angle θ by A (θ). The curve of the ideal sine function of the impedance change of the other sensor coil L2 with respect to the change of the rotation angle θ is
It is indicated by (θ). The impedance change curve B (θ) of the other sensor coil L2 corresponds to a cosine function having a phase shifted by 90 degrees with respect to the sensor coil L1. Thus, if the midpoint of the increase / decrease of each curve A (θ), B (θ) is P0 and the amplitude of the shake is P, A (θ) = P0 + Psinθ B (θ) = P0 + Pcosθ can be expressed.

Further, the above-mentioned embodiment shows an embodiment in which two coil pairs that change differentially are provided. In this configuration, the sensor coils arranged every other one are combined into one set of coil pairs (that is, the sensor coils L1 and L3 and the sensor coils L2 and L4 are combined into one set of coil pairs). The impedance of each of the sensor coils L1 to L4 in the one coil pair changes differentially,
Therefore, the increase / decrease in the voltage across the terminals of the sensor coils L1 to L4 exhibits differential characteristics. That is, in the pair of sine-phase sensor coils L1 and L3, assuming that the impedance change of the sensor coil L1 exhibits the functional characteristic “P0 + Psinθ” with respect to the rotation angle θ of the rotation axis MJ as described above, The impedance change of the sensor coil L3 is “P” with respect to the rotation angle θ of the rotation axis MJ.
0-Psin θ ”. Similarly, in the pair of the sensor coils L2 and L4 in the cosine phase, assuming that the impedance change of the sensor coil L2 exhibits the functional characteristic of “P0 + Pcosθ” with respect to the rotation angle θ of the rotation axis MJ as described above, The impedance change of the sensor coil L4 shows a functional characteristic "P0-Pcos θ" with respect to the rotation angle θ of the rotation axis MJ. That is, A ′ (θ) = P0−Psinθ B ′ (θ) = P0−Pcosθ It should be noted that since there is no inconvenience in description even if P is regarded as 1 and omitted, it will be omitted in the following description.

As shown in FIG. 2, each sensor coil L
1, L2, L3, and L4 are excited with a constant voltage or a constant current by a predetermined one-phase high-frequency AC signal (tentatively indicated by sinωt) generated from the AC generation source 30. When the inter-terminal voltages of the sensor coils L1, L2, L3, L4 are represented by Vs, Vc, Vsa, and Vca, respectively, these can be expressed as follows with the rotation angle θ to be detected as a variable. Vs = A (θ) sin ωt = (P0 + sinθ) sin
ωt Vsa = A ′ (θ) sin ωt = (P0-sinθ) s
inωt Vc = B (θ) sin ωt = (P0 + cosθ) sin
ωt Vca = B ′ (θ) sin ωt = (P0−cos θ) s
The inωt arithmetic circuit 31 takes out the difference between the terminal voltages of the sensor coils L1, L2, L3, and L4 for each coil pair, and outputs the AC output having a predetermined periodic amplitude function as an amplitude coefficient, as described below. A signal is generated for each coil pair. That is, the output voltages Vs, Vc, Vsa, and Vca of the sensor coils L1, L2, L3, and L4 are input to the arithmetic circuit 31 and are calculated according to the following arithmetic expressions, so that the detection target position θ is calculated from the arithmetic circuit 31. Two AC output signals each having an amplitude exhibiting a sine and cosine function characteristic corresponding to (i.e., two AC output signals having an amplitude function characteristic 90 degrees out of phase with each other) are generated. Vs-Vsa = (P0 + sinθ) sinωt- (P0-sinθ) sinωt = 2sinθsinωt Vc-Vca = (P0 + cosθ) sinωt- (P0-cosθ) sinωt = 2cosθsinωt

In this way, two periodic amplitude functions (sin θ and c) corresponding to the rotation angle θ of the rotation axis MJ to be detected.
osθ) as the amplitude coefficient, similar to the resolver, 2
Two AC output signals (sin θ sin ωt and cos θs
inωt) can be generated. That is, two AC output signals (sin θsin ωt and cos θsi) having as amplitude coefficients two periodic amplitude functions (sin θ and cos θ) that swing positively and negatively with the midpoint of the increase / decrease change as the zero point.
nωt) can be generated. FIG. 3B schematically shows this state only for the θ component (here, the component at time t is not shown). in this way,
Compared with the conventional resolver, in the present invention, only the primary coil needs to be provided, and the secondary coil for inductive output is unnecessary, so the coil configuration is simple and the rotary position detecting device having a simple structure. Can be provided. It should be noted that, in order to extract the difference in the voltage between the terminals of each coil for each coil pair, the sensor coils L1 and L3 are differentially connected without using a special arithmetic circuit 31, and the sensor coil L
By differentially connecting 2 and L4, the difference between each is "Vs-
The circuit may be simply configured to obtain output AC signals corresponding to "Vsa" and "Vc-Vca".

Amplitude functions sin θ and co in the AC output signals sin θ sin ωt and cos θ sin ωt having the sine and cosine function characteristics output from the arithmetic circuit 31.
The phase component θ of sθ is measured by the phase detection circuit (or the amplitude / phase conversion means) 32 to detect the rotational position θ of the detection target.
Can be detected as an absolute value. The phase detection circuit 32 may be configured using, for example, the technique disclosed in Japanese Patent Application Laid-Open No. 9-126809 filed by the present applicant. For example, the first AC output signal sin θsi
By electrically shifting nωt by 90 degrees, the AC signal s
sin θ cos ωt is generated, and this and the second AC output signal cos θ sin ωt are added and subtracted to obtain sin
Two (ωt + θ) and sin (ωt−θ) phase-shifted AC signals (signals obtained by converting the phase component θ into an AC phase shift) corresponding to θ are generated and the phases thereof are generated. The rotational position detection data can be obtained by measuring θ. Alternatively, an RD converter used for processing a known resolver output signal may be used as the phase detection circuit 32.
The detection processing of the phase component θ in the phase detection circuit 32 is not limited to digital processing, and may be analog processing using an integration circuit or the like. Alternatively, the digital detection data indicating the rotational position θ may be generated by the digital phase detection process, and then the analog detection data indicating the rotational position θ may be obtained by analog conversion. Of course, without providing the phase detection circuit 32, the output signal sin θ of the arithmetic circuit 31
Alternatively, sin ωt and cos θ sin ωt may be output as they are. For example, in the case where the arithmetic circuit 31 outputs a three-phase signal similar to that for synchro, such an application form is possible.

In the above embodiment, the sensor coils L1, L2, L3 and L4 are arranged only within a limited predetermined angular range (60 degree range) within one rotation. Therefore, the size of the sensor head SH does not have to be the one shown in FIG. 1, but can be a size corresponding to a narrower range. By doing so, even if there is an obstacle in a predetermined area of the sensor rotor plate RP, it is possible to avoid the obstacle and install the detection device.
Further, the sensor rotor plate RP as described above is attached to the rotating body.
Since the rotational position can be detected simply by additionally attaching the sensor head SH and arranging the sensor head SH in accordance with this, the rotational position detecting device can be easily equipped even with an existing rotating body. Like As described above, the rotary position detecting device according to the present invention is installed in a case where the rotary position detecting device is installed in an existing machine later, or in an engine motor for automobiles where machines are densely packed in a predetermined range. It is especially effective when That is, when an obstacle already exists in a predetermined rotation angle range of the rotation axis MJ and installation of a conventional rotary position detecting device having a size corresponding to one full rotation is impossible, It is advantageous that the rotary position detecting device according to the present invention can be applied to a position in an angular range where no position exists, which is advantageous. Of course, in any of the embodiments, the detection target rotation axis MJ itself may be capable of continuous rotation of one full rotation or more, or may be rotated only within a limited angular range of less than one rotation ( That is, it may reciprocally swing).

In the detecting device according to the present invention, the position is detected by the magnetic action in the sensor head SH. Therefore, when an undesired magnetism is exerted from the outside, the position detecting accuracy may be adversely affected. . In order to deal with this point, according to one embodiment, a magnetic shield member that shields external magnetism is provided around the sensor head SH. In particular, when the position detecting device according to the present invention is applied to an engine motor for an electric vehicle as described above, the engine motor for an electric vehicle has a large output and therefore has a lot of leakage magnetism to the outside. It is necessary to take magnetic shield measures. 4 and 5
Shows an example in which such magnetic shield measures are taken.
FIG. 4A shows a plurality of detection units S1 to S as shown in FIG.
6 is a schematic sectional view showing an embodiment in which the entire sensor head SH including 4 (simply indicated by S in FIG. 4) is covered with a housing K made of a magnetic material. In this case, a magnetic circuit of magnetism from the outside is formed through the magnetic body of the housing K, and the inside detection unit S can be shielded so that the outside magnetism does not enter. In this case, it is preferable that the entire magnetic core C of each detection unit S be covered with a diamagnetic material (nonmagnetic good conductor such as copper, aluminum, or brass) A. The magnetism from the outside is attenuated by the eddy current loss at the location of the diamagnetic body (non-magnetic good conductor), so that the external magnetism leaking inside the detection unit S is attenuated. Therefore, it becomes possible to accurately detect the rotational position. FIG. 4B is a schematic cross-sectional view showing a modified example of the magnetic coil C, and shows an example in which an independent magnetic core C is arranged in the sensor coil L. Figure 4
As shown in (B), as the magnetic core C, without using the magnetic core C formed in the shape of “C” (see FIG. 1C), the magnetic core C is simply formed into a cylindrical shape or a rectangular parallelepiped shape. The formed magnetic core C may be used, and this makes it possible to configure the sensor head SH to be smaller and simpler, and thus to provide a rotary position detection device that is advantageous for installation in a narrow space. There is an advantage that it can be done.

The end of the magnetic core C of the detecting portion S of the sensor head SH described above is connected to the sensor rotor plate RP.
However, the present invention is not limited to this and may be arranged so as to be directed in the radial direction. FIG. 4C is a schematic sectional view showing an example in which the magnetic core C of the sensor coil L is arranged so as to be oriented in the radial direction of the sensor rotor plate RP.
In FIG. 4 (C), the same reference numerals as those in FIGS. 4 (A) and 4 (B) indicate elements having the same function, and therefore the above description is cited and the same description is not repeated. In FIG. 4C, the end of the magnetic core C of the sensor coil L is directed inward in the radial direction of the sensor rotor plate RP, and faces the outer peripheral side surface of the sensor rotor plate RP through a gap. . In this case, because of the predetermined shape of the sensor rotor plate RP (for example, an appropriately designed shape such as 6 teeth or 6 petals as shown in FIG. 1A), the end portion of the magnetic core C and the sensor rotor plate RP are The distance of the gap formed in the radial direction between the outer peripheral side surface of the RP changes depending on the rotational position. Due to this change in the facing air gap distance, the amount of magnetic flux penetrating the sensor coil L through the magnetic core C changes, so that the self-inductance of the sensor coil L changes and the impedance of the sensor coil L changes. Therefore, the rotational position can be detected in the same manner as the embodiment shown in FIG. In the case of FIG. 4C, the axial length of the outer peripheral side surface of the sensor rotor plate RP is set to be slightly longer. As a result, the sensor rotor plate R
Even if P causes some mechanical shake in the thrust direction, the distance of the air gap formed in the radial direction between the end of the magnetic core C and the outer peripheral side surface of the sensor rotor plate RP does not change, and the detection accuracy is improved. Does not decrease. Therefore, also in this case, in an environment or machine in which the sensor rotor plate RP is likely to cause mechanical shake in the thrust direction, it is possible to detect a rotational position that is not affected by mechanical shake in the thrust direction. There is.

In the above-mentioned example, an example is shown in which each detecting section S is individually covered with a diamagnetic material (non-magnetic good conductor) A, but as another structural example of the magnetic shield member, a magnetic material is used. The entire surface of the housing K may be covered with a diamagnetic material such as copper. In this case, a thin layer made of a diamagnetic material may be formed on the surface of the housing K by, for example, plating the surface of the housing K made of a magnetic material with copper. FIG. 5 shows an example in which such magnetic shield measures are taken. The entire sensor head SH including the plurality of detectors S1 to S4 is covered with a housing K made of a magnetic material K1, and a thin layer of a diamagnetic material K2 such as copper is applied to the surface of the housing K by plating or the like. In the example of FIG. 5, the base K3 of the housing K is made of a non-magnetic non-conductive material such as plastic and the strength is increased, so that the magnetic body K1 can be made light and thin. The magnetic cores of the detection units S1 to S4 are of the same type as that shown in FIG. 4B, such as a cylindrical shape, a rectangular shape, or a “C” shape (see FIG.
(A) (see (A)). The rear surface of the housing K, that is, the housing K
A layer of a good non-magnetic conductor may be formed between the casing and the casing K3. Also in the example shown in FIGS. 4A and 4B, the housing K may be configured to be coated (copper plated or the like) with a non-magnetic and highly conductive material.

The technical idea of installing a magnetic shield member made of a material having good non-magnetic conductivity and shielding external magnetism by the eddy current loss at the location of the magnetic response member is based on the above-mentioned sensor head SH. Not only the example in which the magnetic shield is applied to the housing K of FIG.
It can also be realized by providing a magnetic shield on the side.
In FIG. 6, the rotational position detection device includes a stator portion 23 including a coil portion, a rotary shaft 20 made of a magnetic body to which a rotational motion to be detected is given, and a predetermined magnetically responsive member attached to the rotary shaft 20. The rotor portion 21 having a shape is included, and the distance of the gap between the rotor portion 21 and the coil portion changes according to the rotation position according to the rotation of the rotating shaft 20. The impedance of the coil portion is changed, and an output signal corresponding to this impedance change is generated. Any known configuration may be used as the specific configuration of the rotational position detecting device. The characteristic feature of this embodiment is that the joint portion for fixing the rotor portion 21 to the rotating shaft 20 is constituted by a magnetic shield member 22 made of a diamagnetic material (for example, copper). As a result, the external magnetism Φ leaking to the rotor portion 21 through the rotating shaft 20 is attenuated by the eddy current loss at the location of the magnetic shield member 22, and the rotor portion 21
Also, external magnetism leaking to the magnetic circuit for detection of the stator portion 23 is shielded. Therefore, it is possible to detect the position accurately without being affected by the external magnetism. Even in the apparatus shown in FIG. 6, a magnetic shield member for shielding the coil portion of the stator portion 23 from the outside may be further provided around the coil portion.

When a good conductor such as copper is used as the magnetically responsive member, the inductance of the coil decreases due to the eddy current loss, and the voltage between the terminals of the coil decreases as the magnetically responsive member approaches. It will be. Also in this case,
The position detection operation can be performed in the same manner as described above. Further, as the magnetic response member, a hybrid type member in which a magnetic body and a conductor are combined may be used. In addition, in the type that detects the rotational position of the swinging motion within the rotation range of less than one rotation, the magnetic response member (the sensor rotor plate RP in the above-described embodiments) is used in each of the above embodiments. Fixed, sensor coils L1, L2
The sensor head SH in which L3 and L4 are arranged may be moved according to the displacement of the detection target. Further, in the above embodiment, the number of output AC signals (the number of phases) is two phases of sine and cosine (that is, resolver type), but it is not limited to this. For example, three phases (the amplitude function of each phase is sin θ, sin (θ + 120), sin
(Such as (θ + 240)).

As a method of alternating-current excitation of the sensor coils, at least two sensor coils are each si.
It is also possible to use a known two-phase excitation method in which nωt and cosωt are separately excited. However, the one-phase excitation as described in the above embodiment is superior in various aspects such as simplification of the configuration and temperature drift compensation characteristics. In the present invention, the voltage generated in the coil or the voltage between the terminals of the coil is not necessarily limited to the voltage detection type circuit configuration, and should be broadly interpreted.
Those that adopt a current detection type circuit configuration are also included in the range. In short, any circuit configuration can be used as long as it can generate an analog voltage or current according to the change in the impedance of the coil and detect it.

[0035]

As described above, according to the present invention, only the primary coil needs to be provided, and the secondary coil is not required. Therefore, it is possible to provide a rotary type position detecting device having a small size and a simple structure. it can. Further, by calculating the output signal of the coil, it is possible to obtain an output signal showing the amplitude coefficient characteristic of a true sine function or a cosine function in which the amplitude coefficient component swings positively and negatively, so that the coil configuration is simple, and further, It is possible to provide a rotary type position detection device having a small size and a simple structure. Further, it is possible to provide a rotary position detection device capable of accurate position detection without being affected by external magnetism.

[Brief description of drawings]

1A and 1B show one embodiment of a rotary type position detecting device according to the present invention, where FIG. 1A is a schematic front view showing the structure of the rotary type position detecting device, FIG. 8) is an enlarged perspective view of a detection unit in the rotary position detection device.

FIG. 2 is an electric circuit diagram relating to a sensor coil in the rotary position detecting device shown in FIG.

3 is a diagram for explaining the detection operation of the embodiment of FIG.
(A) shows an ideal curve of impedance change of each detection coil with respect to change of rotation angle θ, and (B) shows
The figure which shows the amplitude change characteristic with respect to the rotation angle (theta) of the output signal obtained by calculating the output voltage of each detection coil.

FIG. 4 shows another example of a sensor head having a housing that performs a magnetic shield function,
(A) is a schematic cross-sectional view showing an embodiment in which the entire sensor head is covered with a magnetic material housing, (B) is a schematic cross-sectional view showing a modification of the magnetic material core of the sensor coil, and (C) is a magnetic material of the sensor coil. 5 is a schematic cross-sectional view showing an example in which the body core is arranged so as to be oriented in the radial direction of the sensor rotor plate.

FIG. 5 is a schematic perspective view showing still another embodiment of the sensor head.

FIG. 6 is a schematic perspective view showing an embodiment of a rotational position detecting device having a magnetic shield function in a rotor section.

[Explanation of symbols]

SH sensor head S, S1, S2, S3, S4 detector L, L1, L2, L3, L4 sensor coil C, C1, C2, C3, C4 Magnetic core P body plate RP sensor rotor plate (magnetic response member) T mounting screw M motor MJ rotation axis K housing SR shield ring 20 rotation axis 21 rotor 22 Magnetic shield member 23 Stator 30 AC source 31 arithmetic circuit 32 Phase detection circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F063 AA35 BD16 CA35 DA01 DD06                       GA03 GA33 GA36 KA01 LA01                       LA03                 2F077 AA25 AA27 FF03 FF13 JJ02                       JJ06 NN02 NN21 PP06 QQ03                       TT06 VV01

Claims (7)

[Claims] 1. A coil unit in which at least one pair of coils excited by an AC signal are arranged over a predetermined partial rotation angle range, and each coil in the pair of coils corresponds to a predetermined rotation angle. A magnetically responsive member that is arranged so as to be spaced apart from each other with a rotational displacement relative to the coil portion, and that the member and the coil portion are relative to each other according to the rotation of the detection target. The rotational position of the coil changes, the impedance of the coil is changed according to the relative rotational position, and the voltage generated in the coil is changed based on the impedance change while the relative rotational position changes over a predetermined rotation angle range. The voltage of each coil in the pair of coils is increased or decreased so as to exhibit a differential characteristic. And a voltage difference generated between the coils in the pair of coils and an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is generated for each coil. A rotary position detecting device, wherein the cyclic amplitude function of each of the AC output signals differs in a periodic characteristic by a predetermined phase. 2. The coil pair is provided in two pairs, and the circuit generates an AC output signal having a sine function as an amplitude coefficient and an AC output signal having a cosine function as an amplitude coefficient from each coil pair. The rotary position detecting device according to claim 1, wherein 3. Each coil of the coil section includes a magnetic core, and an area of the magnetic response member facing the magnetic core changes according to rotation, thereby causing impedance change of the coil. The rotary type position detection device according to claim 1 or 2. 4. The magnetic core is formed in a predetermined C shape, and the coils of the coil section are arranged at opposite ends of the magnetic core, and the coil sandwiches the magnetic response member. The rotary type position detecting device according to claim 3, wherein the rotary type position detecting device is made less susceptible to mechanical shake in the thrust direction of the detection target rotary shaft. 5. The rotational position detecting device according to claim 1, wherein a magnetic shield member for shielding the coil portion from the outside is provided around the coil portion. 6. A rotor portion having a predetermined shape and made of a magnetically responsive member, which is attached to a detection target rotating shaft made of a magnetic material,
A stator having a coil portion excited by an AC signal, wherein a relative rotational position of the magnetic response member and the coil portion changes according to rotation of the rotating shaft, and the relative rotational position changes. In the rotational position detecting device configured to change the impedance of the coil portion according to the above and generate an output signal according to the change in impedance, a magnetic shield member is provided at a joint portion that fixes the rotor portion to the rotation shaft. A rotational position detecting device, characterized in that the magnetic shield member shields external magnetism leaking to the rotor portion through the rotating shaft. 7. A rotor unit having a predetermined shape, which is made of a magnetically responsive member, is attached to a rotary shaft to be detected, and a stator having a coil unit that is excited by an alternating current signal. The rotor unit according to the rotation of the rotary shaft. The relative rotational position of the magnetically responsive member and the coil portion changes, the impedance of the coil portion is changed according to the change of the relative rotational position, and an output signal corresponding to this impedance change is generated. In the rotational position detecting device, a magnetic shield member for shielding the coil part from the outside is provided around the coil part.